xmltools.py

   1 from xml.dom import Node, minidom
   2
   3 XMLNS_INTERFACE = "http://zero-install.sourceforge.net/2004/injector/interface"
   4
   5 def data(node):
   6         """Return all the text directly inside this DOM Node."""
   7         return ''.join([text.nodeValue for text in node.childNodes
   8                         if text.nodeType == Node.TEXT_NODE])
   9
  10 def set_data(elem, value):
  11         """Replace all children of 'elem' with a single text node containing 'value'"""
  12         for node in elem.childNodes:
  13                 elem.removeChild(node)
  14         if value:
  15                 text = elem.ownerDocument.createTextNode(value)
  16                 elem.appendChild(text)
  17
  18 def indent_of(x):
  19         """If x's previous sibling is whitespace, return its length. Otherwise, return 0."""
  20         indent = x.previousSibling
  21         if indent and indent.nodeType == Node.TEXT_NODE:
  22                 spaces = indent.nodeValue.split('\n')[-1]
  23                 if spaces.strip() == '':
  24                         return len(spaces)
  25         return 0
  26
  27 def insert_before(new, next):
  28         indent_depth = indent_of(next)
  29         new_parent = next.parentNode
  30
  31         prev = next.previousSibling
  32         if prev and prev.nodeType == Node.TEXT_NODE:
  33                 next = prev
  34
  35         new_parent.insertBefore(new, next)
  36         if indent_depth:
  37                 text = new_parent.ownerDocument.createTextNode('\n' + (' ' * indent_depth))
  38                 new_parent.insertBefore(text, new)
  39
  40 def insert_element(new, parent, before = []):
  41         indent = indent_of(parent) + 2  # Default indent
  42         last_element = None
  43         for x in parent.childNodes:
  44                 if x.nodeType == Node.ELEMENT_NODE:
  45                         indent = indent or indent_of(x)
  46                         if x.localName in before:
  47                                 parent.insertBefore(new, last_element.nextSibling)
  48                                 break
  49                         last_element = x
  50         else:
  51                 if last_element:
  52                         parent.insertBefore(new, last_element.nextSibling)
  53                 else:
  54                         had_children = bool(list(child_elements(parent)))
  55                         parent.appendChild(new)
  56                         if not had_children:
  57                                 final_indent = '\n' + (' ' * indent_of(parent))
  58                                 parent.appendChild(parent.ownerDocument.createTextNode(final_indent))
  59         if indent:
  60                 indent_text = parent.ownerDocument.createTextNode('\n' + (' ' * indent))
  61                 parent.insertBefore(indent_text, new)
  62
  63 def create_element(parent, name, uri = XMLNS_INTERFACE, before = []):
  64         """Create a new child element with the given name.
  65         Add it as far down the list of children as possible, but before
  66         any element in the 'before' set. Indent it sensibly."""
  67         new = parent.ownerDocument.createElementNS(uri, name)
  68         insert_element(new, parent, before)
  69         return new
  70
  71 def remove_element(elem):
  72         """Remove 'elem' and any whitespace before it."""
  73         parent = elem.parentNode
  74         prev = elem.previousSibling
  75         if prev and prev.nodeType == Node.TEXT_NODE:
  76                 if prev.nodeValue.strip() == '':
  77                         parent.removeChild(prev)
  78         parent.removeChild(elem)
  79
  80 def format_para(para):
  81         """Turn new-lines into spaces, removing any blank lines."""
  82         lines = [l.strip() for l in para.split('\n')]
  83         return ' '.join(filter(None, lines))
  84
  85 def attrs_match(elem, attrs):
  86         for x in attrs:
  87                 if not elem.hasAttribute(x): return False
  88                 if elem.getAttribute(x) != attrs[x]: return False
  89         return True
  90
  91 def child_elements(parent):
  92         """Yield all direct child elements."""
  93         for x in parent.childNodes:
  94                 if x.nodeType == Node.ELEMENT_NODE:
  95                         yield x
  96
  97 def children(parent, localName, uri = XMLNS_INTERFACE, attrs = {}):
  98         """Yield all direct child elements with this name and attributes."""
  99         for x in parent.childNodes:
 100                 if x.nodeType == Node.ELEMENT_NODE:
 101                         if x.nodeName == localName and x.namespaceURI == uri and attrs_match(x, attrs):
 102                                 yield x
 103
 104 def singleton_text(parent, localName, uri = XMLNS_INTERFACE):
 105         """Return the text of the first child element with this name, or None
 106         if there aren't any."""
 107         elements = list(children(parent, localName, uri))
 108         if elements:
 109                 return data(elements[0])
 110
 111 def set_or_remove(element, attr_name, value):
 112         if value:
 113                 element.setAttribute(attr_name, value)
 114         elif element.hasAttribute(attr_name):
 115                 element.removeAttribute(attr_name)